1. Field of the Invention
This invention relates to a method for the production of an aqueous dispersion of a N-substituted N',N'-alkylene urea. More particularly, this invention relates to a novel method for the production of an aqueous dispersion of a N-substituted N',N'-alkylene urea by the reaction of an alkylene imine with an isocyanate.
2. Description of Prior Art
Such N-substituted N',N'-alkylene ureas as diphenylmethane-bis-4,4'-N,N'-dialkylene ureas (hereinafter referred to as "DPU") and N-alkyl-N',N'-alkylene ureas are compounds known to the art and are utilized extensively as cross-linking agent for resin, textile processing agents such as softening agent, waterproofing agent and wrinkleproofing agent, paint and ink, and resin modifiers. Further, because they have high cross-linking rates and are capable of treatments at low temperatures, they prove to be important industrial materials [Textile Res. J. 31, 57 (1961)].
Heretofore, water insoluble N-substituted N',N'-alkylene urea powders have been handled, in most cases, as dissolved in organic solvents such as dimethylformamide (DMF), dioxane, acetone and alcohols. These N-substituted N',N'-alkylene ureas, when handled in the form of dust and suffered to be inhaled, can cause harm to the human body and, when handled in the form of a solution in an organic solvent without due care, can induce fire hazard. In the circumstance, the desirability of handling these compounds in a safer and more convenient form of aqueous dispersion instead of powder or solution has found growing recognition.
A method for producing an alkylene urea by causing an alkylene isocyanate having at least 10 carbon atoms to react with ethylene imine in water preferably in the presence of a dispersant or an emulsifier has been known to the art (British Pat. No. 799,045). By such methods, stable aqueous dispersion cannot be obtained, unless the other component is added into the resulted aqueous dispersion.
An object of this invention, therefore, is to provide a novel method for the production of an aqueous dispersion of a N',N'-alkylene urea.
Another object of this invention is to provide a novel method for the production of a stable aqueous dispersion of a N-substituted N',N'-alkylene urea by the reaction of an alkylene imine with an isocyanate in water in the presence of a specified surface active agent.